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Understanding Cellular Respiration and ATP

Feb 7, 2025

Lecture Notes: Cellular Respiration and ATP Production

Introduction

  • Cells are constantly performing processes requiring energy, specifically ATP.
  • ATP (Adenosine Triphosphate) contains three phosphates; when one is broken, energy is released, converting to ADP (Adenosine Diphosphate).
  • All cells, prokaryotic or eukaryotic, must produce ATP, but methods vary.

Aerobic Cellular Respiration

  • Focus on eukaryotic cells with mitochondria, key for ATP production.
  • Formula Similarity:
    • Cellular respiration is the reverse of photosynthesis.
    • Photosynthesis produces glucose; cellular respiration uses glucose to produce ATP.

Photosynthesis vs. Cellular Respiration

  • Photosynthetic organisms perform both, creating glucose and breaking it for ATP.
  • Non-photosynthetic beings (humans, amoebas) obtain glucose from food.

Major Steps of Cellular Respiration

  1. Glycolysis

    • Location: Cytoplasm
    • Oxygen Requirement: None
    • Process: Converts glucose to pyruvate.
    • Energy Yield: 2 ATP and 2 NADH.
    • NADH is a coenzyme important for electron transfer.

  2. Krebs Cycle (Citric Acid Cycle)

    • Location: Mitochondria
    • Oxygen Requirement: Yes
    • Process: Pyruvate is oxidized, producing CO2.
    • Energy Yield: 2 ATP, 6 NADH, 2 FADH2.
    • FADH2, like NADH, assists in electron transfer.

  3. Electron Transport Chain

    • Location: Mitochondria
    • Oxygen Requirement: Yes
    • Process: Electrons from NADH and FADH2 transferred, creating a proton gradient.
    • ATP Synthase: Enzyme that synthesizes ATP by adding phosphates to ADP.
    • Final Electron Acceptor: Oxygen, which forms H2O.
    • Energy Yield: Approximately 34 ATP, though this number can vary.

ATP Production Summary

  • Total ATP: Approximately 38 ATP per glucose molecule in ideal conditions.
  • Variability in ATP production exists due to different cellular conditions.

Alternative ATP Production: Fermentation

  • Occurs when oxygen is unavailable.
  • Less efficient than aerobic respiration but still produces ATP.

Importance of ATP Production

  • Cyanide blocks electron transport chain, demonstrating ATP's critical role.
  • Mitochondrial disorders impact ATP production; ongoing research is crucial.

Conclusion

  • Understanding ATP production is vital for cell function and health.
  • Continued research is important for treating mitochondrial disorders.

Stay Curious - Encouragement to remain inquisitive and explore further.

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